My advice would be to work out what fish you simply must have and then work from there. For me it was German Blue Rams Clown loaches are lovely but your right they can grow very large about 25cm I think max?
Jungle777 do your cardinals just stay in one place ? i have 15 of them and there never away from one of my swords.
No my cardinals venture all over really, they shoal now and then but I thought another 8 or so (giving me 16) would look better. I'm just worried i dont have room? I was also considering some more Rams but I'm no sure how many should be kept together? I presume mine are the same as your 'German Blue Rams' as mine are flurescent blue - the male is a lot bigger than the 2 females...